1. Field of the Invention
This invention relates generally to therapeutic beds, and more particularly to beds with a patient support platform operable to rotate about a longitudinal axis of the platform.
2. Description of the Related Art
One of the problems in the art of prone positioning therapeutic beds is to provide data and power connections to the bed for both the power and controller equipment that moves the bed and for the patient monitoring systems on the bed. To allow unrestricted rotation of the bed of WO 99/62454, for example, electrical power has been provided by wire brushes at the interface between the rotating part of the bed and the nonrotating part of the bed. However, due to vibration and other abrupt movements, such wire brushes cause problems of electrical intermittence, which can be detrimental to the therapy of the patient. A direct power or data carrier would be preferable to eliminate such intermittence, provided that the wired connection is capable of articulation during movement of the rotating part of the bed into the prone position, and provided that a mechanism is provided to prevent excessive rotation in any one direction.
In U.S. patent application Ser. No. 09/821,552 filed Mar. 29, 2001, and Ser. No. 09/884,749 filed Jun. 19, 2001 now U.S. Pat. No. 6,566,833, the first of which is herein incorporated by reference, a prone positioning bed is disclosed that encompasses several distinct innovations. This divisional application is directed to a rotation limiter to prevent excessive rotation of the patient support platform in any one direction.
A therapeutic bed in accordance with the present invention is provided comprising a base frame, a patient support platform rotatably mounted on the base frame for rotational movement about a longitudinal rotational axis of the patient support platform, and a drive system for rotating the patient support platform on the base frame. A direct, wired connection is provided to the patient support platform that allows for a complete rotation of the patient support platform in either direction. The necessary electrical wires are housed within a chain-like cable carrier that is disposed within an annular channel attached to the patient support platform. An annular cover is installed adjacent the annular channel to retain the cable carrier within the annular channel, but the annular cover is not attached to the annular channel. Rather, the annular cover is attached to the nonrotating part of the bed. One end of the cable carrier is attached to the annular channel, and the other end is attached to the annular cover. The length of the cable carrier is sufficient to allow a full 360 degree rotation of the patient support platform in either direction from 0 degrees supine flat while maintaining a direct electrical connection.
More preferably, the direct, wired electrical connection to the patient support platform may be provided with a flat ribbon cable or flexible printed circuit board (PCB) cable in lieu of a chain-like cable carrier. The cable resides within an annular channel attached to the patient support platform, and an annular cover is fastened to a flange of the annular channel such that a gap exists between the annular channel and the annular cover around the outer periphery. One end of the cable is attached to the annular channel, which provides power and electrical signals to the rotating part of the bed, and the other end of the cable passes through the gap between the annular channel and the annular cover and is connected to the electrical apparatus on the nonrotating part of the bed. Like the cable carrier mentioned above, the cable has a length sufficient to allow a full rotation of the patient support platform in either direction while maintaining a direct electrical connection between the nonrotating and rotating parts of the bed. To ensure that the wired electrical connection is not articulated beyond its physical limit as a result of manually rotating the bed in the emergency backup mode, a mechanical stop is provided to limit rotation of the patient support platform to about 365 degrees. Sensors are provided to detect activation of the mechanical stop.
It is an object of this invention to provide a prone positioning therapeutic bed having a direct, wired electrical connection between the rotating part of the bed and the nonrotating part of the bed.
It is another object of this invention to mechanically limit rotation of the bed in either direction to one full 360 degree turn plus about 5 degrees, and to electrically detect when one full turn has been reached.
Further objects and advantages of the present invention will be readily apparent to those skilled in the art from the following detailed description taken in conjunction with the annexed sheets of drawings, which illustrate a preferred embodiment of the invention.